Hemorrhagic shock is a significant complication of surgical, gastrointestinal, and obstetric hemorrhage, but it is most commonly caused by severe trauma. Trauma is the leading cause of death in Americans 44 years-old or younger. During hemorrhagic responses, vascular endothelial cells (ECs) are activated and lose their integrity, contributing significantly to multi-organ failure and lethality. We have recently discovered that cold-inducible RNA-binding protein (CIRP) functions as a damage-associated molecular pattern (DAMP). In an animal model of hemorrhage, CIRP was upregulated in tissues and released into the circulation. Injection of healthy mice with recombinant murine CIRP (rmCIRP) caused an elevation of circulating tissue injury markers and vascular leakage in the lungs in association with increased expression of EC surface adhesion molecules. We then treated primary mouse lung vascular ECs with rmCIRP and observed increased ICAM-1 expression, NAD(P)H oxidase activation, inflammasome assembly and activation, and IL-1? release. We also demonstrated that rmCIRP induced EC pyroptosis. Based on these novel findings, we hypothesize that the CIRP released after hemorrhage causes EC activation and pyroptosis, leading to vascular EC dysfunction and organ damage. We have also identified a 15-mer peptide derived from human CIRP, named C23, which attenuated the expression of EC surface adhesion molecules and proinflammatory cytokines in the lungs as well as serum organ injury markers of hemorrhaged animals. Administration of C23 also reduced vascular leakage in the lungs after hemorrhage. Thus, we further hypothesize that CIRP antagonism by C23 represents a novel adjunct therapy for traumatic hemorrhage resuscitation via attenuation of EC damage. Accordingly, we plan to test the following four Specific Aims: (1) to confirm the pivotal role of CIRP in causing vascular EC injury after hemorrhage; (2) to determine the effect of CIRP on the activation of vascular ECs after hemorrhage; (3) to examine effects of CIRP on the induction of EC pyroptosis after hemorrhage; and (4) to develop an anti-CIRP peptide as a therapeutic adjunct for EC damage and mortality after hemorrhage. These proposed studies will lead to a new direction towards the development of innovative therapeutics as resuscitation adjuncts for patients suffering from trauma and hemorrhagic shock.